When a photograph is taken by a camera, an image is collected by a lens and retained in some medium. The image is generally produced by the light captured by the lens for the brief duration during which the shutter of the camera is open.
When images are captured outdoors, haze tends to adversely impact the quality of the background. More specifically, weather and other atmospheric phenomena, such as haze, greatly reduce the visibility of distant regions in images of outdoor scenes. Such haze is generated when light is refracted or obstructed by moisture particles and other particulate matter residing in the atmosphere.
Manipulating a digital image to remove the effect of haze, often termed “dehazing”, is a challenge for photography experts. Images of outdoor scenes are usually degraded by atmospheric particles, such as haze, fog and smoke, which fade the color and reduce the contrast of objects in the scene. The irradiance received by the camera from the scene point is attenuated along the line of sight. Furthermore, the incoming light is blended with the ambient light reflected into the line of sight by atmospheric particles. Poor visibility becomes a major problem for outdoor video surveillance applications.
Haze removal techniques are commonly employed by photographers. Typically, haze removal is usually done across the entire image. This creates a problem when an image has a narrowed depth of field, in which the subjects on the foreground usually have a sharper focus than those on the background. When haze removal applies, all subjects would typically be applied uniformly, without accounting for the blurred background.
As such, there exists a need for a haze removal method and system for selectively applying haze removal techniques to portions of a digital image which are most afflicted.